01 January 1970 8 4K Report

Is Uniqueness Their Common and Only Correct Answer?

I. We often say that xx has no physical meaning or has physical meaning. So what is "physical meaning" and what is the meaning of "physical meaning "*?

"As far as the causality principle is concerned, if the physical quantities and their time derivatives are known in the present in any given coordinate system, then a statement will only have physical meaning if it is invariant with respect to those transformations for which the coordinates used are precisely those for which the known present values remain invariant. I claim that all assertions of this kind are uniquely determined for the future as well, i.e., that the causality principle is valid in the following formulation: From knowledge of the fourteen potentials ......, in the present all statements about them in the future follow necessarily and uniquely insofar as they have physical meaning" [1].“Hilbert's answer is based on a more precise formulation of the concept of causality that hinges on the distinction between meaningful and meaningless statements.”[2]

Hawking said [4], "I take the positivist view that a physical theory is nothing more than a mathematical model, and it is pointless to ask whether it corresponds to the real. All one can seek is that its predictions agree with its observations."

Is there no difference between physics and Mathematics? We believe that the difference between physics and mathematics lies in the fact that physics must have a physical meaning, whereas mathematics does not have to. Mathematics can be said to have a physical meaning only if it finds a corresponding expression in physics.

II. We often say, restore naturalness, preserve naturalness, the degree of unnaturalness, Higgs naturalness problem, structural naturalness, etc., so what is naturalness or unnaturalness?

“There are two fundamental concepts that enter the formulation of the naturalness criterion: symmetry and effective theories. Both concepts have played a pivotal role in the reductionist approach that has successfully led to the understanding of fundamental forces through the Standard Model. ” [6]

Judging naturalness by symmetry is a good piece of criteria; symmetry is the only result of choosing stability, and there seems to be nothing lacking. But using effective theories as another criterion must be incomplete, because truncate obscures some of the most important details.

III. We often say that "The greatest truths are the simplest"(大道至简†), so is there a standard for judging the simplest?

"Einstein was firmly convinced that all forces must have an ultimate unified description and he even speculated on the uniqueness of this fundamental theory, whose parameters are fixed in the only possible consistent way, with no deformations allowed: 'What really interests me is whether God had any choice in the creation of the world; that is, whether the necessity of logical simplicity leaves any freedom at all' ”[6]

When God created the world, there would not have been another option. The absolute matching of the physical world with the mathematical world has shown that as long as mathematics is unique, physics must be equally unique. The physical world can only be an automatic emulator of the mathematical world, similar to a Cellular Automata.

It is clear that consensus is still a distant goal, and there will be no agreement on any of the following issues at this time:

1) Should there be a precise and uniform definition of having physical meaning? Does the absence of physical meaning mean that there is no corresponding physical reality?

2) Are all concepts in modern physics physically meaningful? For example, probabilistic interpretation of wave functions, superposition states, negative energy seas, spacetime singularities, finite and unbounded, and so on.

3) "Is naturalness a good guiding principle?"[3] "Does nature respect the naturalness criterion?"[6]

4) In physics, is simplicity in essence uniqueness? Is uniqueness a necessary sign of correctness‡?

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Notes:

* xx wrote a book, "The Meaning of Meaning", which Wittgenstein rated poorly, but Russell thought otherwise and gave it a positive review instead. Wittgenstein thought Russell was trying to help sell the author and Russell was no longer serious [5]. If one can write about the Meaning of Meaning, then one can follow with the Meaning of Meaning of Meaning. In that case, how does one end up with meaning? It is the same as causality; there must exist an ultimate meaning which cannot be pursued any further.

‡ For example, the Shortest Path Principle, Einstein's field equation Gµν=k*Tµν, all embody the idea that uniqueness is correctness (excluding the ultimate interpretation of space-time).

† “万物之始,大道至简,衍化至繁。”At the beginning of all things, the Tao is simple; later on, it evolves into prosperous and complexity. Similar to Leonardo Da Vinci,"Simplicity is the ultimate sophistication." However, the provenance of many of the quotes is dubious.

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References:

[1] Rowe, D. E. (2019). Emmy Noether on energy conservation in general relativity. arXiv preprint arXiv:1912.03269.

[2] Sauer, T., & Majer, U. (2009). David Hilbert's Lectures on the Foundations of Physics 1915-1927: Relativity, Quantum Theory and Epistemology. Springer.

[3] Giudice, G. F. (2013). Naturalness after LHC8. arXiv preprint arXiv:1307.7879.

[4] Hawking, S., & Penrose, R. (2018). The nature of space and time (吴忠超,杜欣欣, Trans.; Chinese ed., Vol. 3). Princeton University Press.

[5] Monk, R. (1990). Ludwig Wittgenstein: the duty of genius. London: J. Cape. Morgan, G. (Chinese @2011)

[6] Giudice, G. F. (2008). Naturally speaking: the naturalness criterion and physics at the LHC. Perspectives on LHC physics, 155-178.

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